Semiconductor devices often include circuitry formed in an active area of a semiconductor die. In order to supply power to the circuits formed on the die, a conventional power distribution network couples the power supply to circuits on the die. Once power is is supplied to circuits on the die, the semiconductor device can perform its intended function.
Circuits in the semiconductor device are subject to faults. One such fault is a short. Shorts may be difficult to detect electrically. Thus, conventional methods of detecting shorts use liquid crystal to sense heat generated by such a short. One conventional method uses a thin layer of liquid crystal poured over the circuits at the top of the die. When power is applied to the die, the liquid crystal phase over some hot spots in the circuits. Due to the phase change, the color of the liquid crystal changes over the hot spots. The centers of areas where the liquid crystal has changed color mark the locations of shorts in the circuit. Consequently, the position of shorts in the circuit can be detected.
Conventional liquid crystal detection this method has several drawbacks. Liquid crystal detection is primarily useful where the short is near a readily accessible surface. If the short is buried, liquid crystal detection may not detect the short because heat is dissipated rapidly in the die. Conventional liquid crystal detection also biases the semiconductor die such that a short will cause the temperature of the surrounding area to rise above the temperature of the liquid crystal phase transition. This biasing may be difficult or time consuming to accomplish. Finally, liquid crystal is carcinogenic. Consequently, health precautions must be taken during use of the liquid crystal.
Accordingly, what is needed is an improved system and method for detecting shorts in a circuit of a semiconductor die. The present invention addresses such a need.